Baclofen is a muscle relaxant and anti-spastic agent. Spasticity is a common symptom of upper motor neuron injury in individuals with cerebral palsy, multiple sclerosis, acquired spinal cord injury, brain injury, and neurodegenerative disorders. Baclofen is a structural analog of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and acts as a GABAB agonist at the level of the spinal cord. Baclofen is the generic name for 4-amino-3-(4-chlorophenyl) butanoic acid. It is a white or off-white, mostly odorless crystalline powder with a molecular weight of 213.66, and it is slightly soluble in water. Baclofen's structural formula is

Baclofen is sold under the tradename LIORESAL® in oral (10 mg or 20 mg tablets) and intrathecal (0.05 mg/mL, 0.5 mg/mL, or 2.0 mg/mL) formulations. The intrathecal formulation is used in conjuction with an implanted programmable pump to provide a constant infusion of the drug. There are several circumstances in which patients treated with oral or intrathecal baclofen must abruptly discontinue therapy. For example, the programmable pump and/or catheter used in intrathecal administration may need to be removed, refilled, or replaced. Moreover, patients taking oral baclofen may be unable to do so during periods of illness, noncompliance, or surgery, for example. Abrupt discontinuation of oral or intrathecal baclofen can result in a severe withdrawal syndrome characterized by rebound increases in muscle tone and spasms, status epilepticus, hallucinations, and a neuromalignant syndrome-like picture potentially resulting in rhabdomyolysis and multisystem organ failure. The current recommended management of baclofen withdrawal is inadequate, and symptoms are often difficult to control. Agarwal et al., A Pilot Study Assessing Pharmacokinetics and Tolerability of Oral and Intravenous Baclofen in Healthy Adult Volunteers, J Child Neurol., (Jul. 14, 2014), http://jcn.sagepub.com/content/early/2014/07/11/0883073814535504.
Thus, there is a clinical need for an intravenous baclofen formulation to prevent or minimize complications resulting from interrupted oral or intrathecal therapy.